Comment on the letter “On the influx of small comets into the Earth's atmosphere II: Interpretation”

Frank et al. (1986a) inferred a terrestrial mass influx of 10 8 g icy comets of ∼10 15 g a −1 . About 20‐40% of the mass of known comets is comprised of chondritic rocky matter, thus the associated influx of chondritic matter is inferred to be at least 2 · 10 14 g a −1 . Iridium‐accumulation evidence indicates a total influx of chondritic extraterrestrial matter having masses in the range 10 −14 to 10 17 g of 7.8 · 10 10 g a −1 , 2500 times smaller; >99% of this infalling matter is in masses <10 −2 g or >10 11 g. For bodies in the 10 7 ‐10 9 g range the inferred flux is 10 8 g a −1 , a factor of 2 · 10 6 lower than that inferred for the Frank et al. comets. Because there must be devolatilized objects in the same population, the actual discrepancy is larger, probably ∼3 · 10 9 .